/*
 * Copyright (C) 2012 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multisets.UnmodifiableMultiset;

import java.util.Comparator;
import java.util.NavigableSet;
import javax.annotation.CheckForNull;

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multisets#unmodifiableSortedMultiset(SortedMultiset)}, split out into
 * its own file so it can be GWT emulated (to deal with the differing elementSet() types in GWT and
 * non-GWT).
 *
 * @author Louis Wasserman
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class UnmodifiableSortedMultiset<E extends @Nullable Object> extends UnmodifiableMultiset<E>
        implements SortedMultiset<E>
{
    UnmodifiableSortedMultiset(SortedMultiset<E> delegate)
    {
        super(delegate);
    }

    @Override
    protected SortedMultiset<E> delegate()
    {
        return (SortedMultiset<E>) super.delegate();
    }

    @Override
    public Comparator<? super E> comparator()
    {
        return delegate().comparator();
    }

    @Override
    NavigableSet<E> createElementSet()
    {
        return Sets.unmodifiableNavigableSet(delegate().elementSet());
    }

    @Override
    public NavigableSet<E> elementSet()
    {
        return (NavigableSet<E>) super.elementSet();
    }

    @CheckForNull
    private transient UnmodifiableSortedMultiset<E> descendingMultiset;

    @Override
    public SortedMultiset<E> descendingMultiset()
    {
        UnmodifiableSortedMultiset<E> result = descendingMultiset;
        if (result == null)
        {
            result = new UnmodifiableSortedMultiset<>(delegate().descendingMultiset());
            result.descendingMultiset = this;
            return descendingMultiset = result;
        }
        return result;
    }

    @Override
    @CheckForNull
    public Entry<E> firstEntry()
    {
        return delegate().firstEntry();
    }

    @Override
    @CheckForNull
    public Entry<E> lastEntry()
    {
        return delegate().lastEntry();
    }

    @Override
    @CheckForNull
    public Entry<E> pollFirstEntry()
    {
        throw new UnsupportedOperationException();
    }

    @Override
    @CheckForNull
    public Entry<E> pollLastEntry()
    {
        throw new UnsupportedOperationException();
    }

    @Override
    public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType)
    {
        return Multisets.unmodifiableSortedMultiset(delegate().headMultiset(upperBound, boundType));
    }

    @Override
    public SortedMultiset<E> subMultiset(
            @ParametricNullness E lowerBound,
            BoundType lowerBoundType,
            @ParametricNullness E upperBound,
            BoundType upperBoundType)
    {
        return Multisets.unmodifiableSortedMultiset(
                delegate().subMultiset(lowerBound, lowerBoundType, upperBound, upperBoundType));
    }

    @Override
    public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType)
    {
        return Multisets.unmodifiableSortedMultiset(delegate().tailMultiset(lowerBound, boundType));
    }

    private static final long serialVersionUID = 0;
}
